Brucellosis
Brucellosis: Excerpt from Professional Guide to Diseases (Eighth Edition)
Brucellosis (also known as undulant fever, Malta fever, or Bang’s disease) is an acute febrile illness transmitted to humans from animals. It's caused by the nonmotile, nonspore-forming, gram-negative coccobacilli of the genus Brucella, notably B. suis (found in swine), B. melitensis (in goats and sheep), B. abortus (in cattle), and B. canis (in dogs). Brucellosis causes fever; profuse sweating; anxiety; general aching; and bone, spleen, liver, kidney, or brain abscesses.
The prognosis is good. With treatment, brucellosis is seldom fatal, although complications can cause permanent disability.
Causes and incidence
Brucellosis is transmitted through the consumption of unpasteurized dairy products and through contact with infected animals or their secretions or excretions. It's most common among farmers, stock handlers, butchers, and veterinarians. Because of such occupational risks, brucellosis infects six times more men than women, especially those between ages 20 and 50; it's less common in children. Because hydrochloric acid in gastric juices kills Brucella bacteria, people with achlorhydria are particularly susceptible to this disease.
Although brucellosis occurs throughout the world, it's most prevalent in the Middle East, Africa, the former Soviet Union, India, South America, and Europe; it's seldom found in the United States. The incubation period usually lasts from 5 to 60 days, but in some cases it can last for months.
Signs and symptoms
Onset of brucellosis is usually insidious, but the disease course falls into two distinct phases. Characteristically, the acute phase causes fever, chills, profuse sweating, fatigue, headache, backache, enlarged lymph nodes, hepatosplenomegaly, weight loss, and abscess and granuloma formulation in subcutaneous tissues, lymph nodes, liver, and spleen. Despite this disease's common name — undulant fever — few patients have a truly intermittent (undulant) fever; in fact, fever is commonly insignificant. It may be observed if the patient goes without treatment for a long time.
The chronic phase produces recurrent depression, sleep disturbances, fatigue, headache, sweating, and sexual impotence; hepatosplenomegaly and enlarged lymph nodes persist. In addition, abscesses may form in the testes, ovaries, kidneys, and brain (meningitis and encephalitis). About 10% to 15% of patients with such brain abscesses develop hearing and visual disorders, hemiplegia, and ataxia. Other complications include osteomyelitis, orchitis and, rarely, subacute bacterial endocarditis, which is difficult to treat.
Diagnosis
In patients with characteristic clinical features, a history of exposure to animals, occupational exposure, or ingestion of high-risk foods suggests brucellosis. Multiple agglutination tests help to confirm the diagnosis. Approximately 90% of patients with brucellosis have agglutinin titers of 1:160 or more within 3 weeks of developing this disease. However, elevated agglutinin titers also follow vaccination against tularemia, Yersinia infection, or cholera; skin tests; or relapse. Agglutinin titers testing can also monitor effectiveness of treatment.
CONFIRMING DIAGNOSIS Three to six cultures of blood and bone marrow and biopsies of infected tissue (for example, the spleen) may provide a definite diagnosis. Culturing is best done during the acute phase.
Hematologic studies indicate an increased erythrocyte sedimentation rate and normal or reduced white blood cell count. Diagnosis must rule out infectious diseases that produce similar symptoms, such as typhoid and malaria.
Treatment
Treatment consists of bed rest during the febrile phase. Antibiotic therapy includes a combination of doxycycline and gentamicin or doxycycline and rifampin. In severe cases, I.V. corticosteroids are given for 3 days, followed by oral corticosteroids. Standard precautions are required until lesions stop draining.
Special considerations
In suspected cases of brucellosis, take a full history. Ask the patient about his occupation and if he has recently traveled or eaten unprocessed food such as dairy products (especially unpasteurized dairy products).
❑During the acute phase, monitor and record the patient's temperature every 4 hours. Be sure to use the same route (oral or rectal) every time. Ask the dietary department to provide between-meal milk shakes and other supplemental foods to counter weight loss. Watch for heart murmurs, muscle weakness, vision loss, and joint inflammation — which may signal complications.
❑During the chronic phase, watch for depression and disturbed sleep patterns. Administer sedatives as ordered, and plan your care to allow adequate rest.
❑Keep suppurative granulomas and abscesses dry. Properly dispose of all secretions and soiled dressings. Reassure the patient that this infection is curable.
❑Before discharge, stress the importance of continuing medication for the prescribed duration. To prevent recurrence, advise the patient to avoid using unpasteurized milk or other dairy products. Warn meat packers and other people at risk of occupational exposure to wear gloves and goggles.
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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